The invention relates to a method for locking or clamping a cylinder dressing on a printing machine cylinder, which includes adjusting a first locking or clamping bar for firmly holding the cylinder dressing and a second locking or clamping bar for likewise holding the cylinder dressing, towards one another in a respective tensioning or tautening direction thereof, and to two devices for locking a cylinder dressing on a printing machine cylinder, with a first locking or clamping bar and a second locking or clamping bar.
Such a device is described in the published German Non-prosecuted Patent Application (DE-OS) 21 05 633. In this heretofore known device, a locking or clamping bar for a starting end of a printing plate is displaceable by a screw, and a locking or clamping bar for the ending end of the plate is displaceable by another screw. In practice, however, a single screw for the plate start and a single screw for the plate end are insufficient for uniformly tautening the printing plate over the width or breadth thereof. A respective plurality of screws are arranged next to one another and are tightened in succession by the pressman at the plate start and the plate end, as illustrated in FIG. 3 of the German non-prosecuted application. The multiplicity of operating locations not only make it more difficult to operate the device manually, but also makes it virtually impossible for the device to be automated.
Another such device is described in the published German Prosecuted Application (DE-AS) 22 00 187. In this device, a plurality of adjusting bolts brace a front locking bar against a cylinder gap wall. For locking up a printing plate, the first locking bar is displaced by the adjusting bolts, so that a leading edge of lay marks coincides with a neutral position. The adjustment of the adjusting bolts to be performed in succession by the pressman is similarly as time-consuming as the tightening of the screws of the device described in The published German Non-prosecuted Patent Application (DE-OS) 21 05 633 noted hereinbefore. After the adjusting bolts have been adjusted, the printing-plate leading edge is laid against the leading edge of the lay marks and tightly clamped, and only then is the printing-plate trailing edge introduced into a rear locking bar and tightly clamped. A disadvantage thereof is that no assurance is provided of uniform tautening of the printing plate in the circumferential direction of the plate cylinder, because it is not possible, with this device, to clamp or lock up the printing plate at both ends thereof. So that the neutral position set before tautening is not lost, during the tautening, the printing-plate leading edge is held locally fixed and only the printing-plate trailing edge is pulled. In the case of many printing plates, the somewhat rope-frictionlike effect active between the printing plates and the plate cylinder, cannot be overcome by the clamping at one end, as described, because the tautening or tensioning forces capable of being exerted upon the printing plate are limited by the construction, and because of the risk of tearing or breaking the printing plate.
The published German Patent Document DE 41 34 309 C2 describes a device for positionally accurate quick-action clamping or locking-up a flexible printing plate on a plate cylinder. A front clamping or locking bar of this device is connected laterally to an actuating device formed of a threaded member and a crank fixedly connected thereto. The front clamping or locking bar is displaceable by a thread of the threaded member. The threaded member is not displaceable in a direction axially parallel with the plate cylinder.
The published German Patent Document DE 41 34 365 C2 describes a further device for positionally accurate quick-action clamping or locking-up a flexible printing plate on a plate cylinder. A front clamping bar of the device described in this reference has assigned thereto, in the middle thereof, a center of rotation fixedly disposed in a cylinder gap and, laterally, an actuating device fastened to a machine frame. The actuating device, via an eccentric disposed on a roller lever, engages in an opening formed in a front lower bar, whereon a front clamping bar is fastened. Neither the eccentric nor the roller lever is displaceable in a direction axially parallel to the plate cylinder.
By the devices described in the two last-mentioned German patent documents, namely DE 41 34 309 C2 and DE 41 34 365 C2, therefore, it is not possible to eliminate satisfactorily the disadvantages inherent in the devices described in the two first-mentioned German patent documents, namely the Non-prosecuted Application (DE-OS) 21 05 633 and the Prosecuted Application (DE-AS) 22 00 187.
The German Patent Document DE 42 08 320 A1 describes a method for correcting skewed positions of flexible printing plates on a plate cylinder. According to this method, a rear clamping or locking bar is loosened or unclamped, the position of a front clamping or locking bar is corrected and the rear clamping or locking bar is thereafter reclamped. It is necessary, in this method, to roll a pressure roller or a backup cylinder over the printing plate after the position of the front clamping bar has been corrected. This is time-consuming and presupposes the presence of a pressure roller or a backup cylinder suitable for the purpose.
It is accordingly an object of the invention to provide a method for locking a cylinder dressing on a printing machine cylinder that is quick-acting and avoids the foregoing disadvantages of heretofore known methods of this general type, and to provide at least one device having few operating locations and by which the method may be performed.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a method for locking a cylinder dressing on a printing machine cylinder, including adjusting a first clamping bar for holding the cylinder dressing, and a second clamping bar for likewise holding the cylinder dressing, towards one another in respective tautening directions thereof, which comprises adjusting the two clamping bars by actuating the same adjusting member, so that, when locking the cylinder dressing, in a first method step, only the first clamping bar is adjusted and, in a second method step, the two clamping bars are adjusted simultaneously.
In accordance with another mode, the method of the invention includes adjusting the two clamping bars towards one another simultaneously, while adjusting the adjusting member in an adjusting direction axially parallel to the printing machine cylinder.
In accordance with a further mode, the method of the invention includes, during tautening, holding the cylinder dressing at the trailing edge thereof by the first clamping bar and at the leading edge thereof by the second clamping bar.
In accordance with a second aspect of the invention, there is provided a device for locking a cylinder dressing on a printing machine cylinder, with a first clamping bar and a second clamping bar, comprising at least one adjusting member adjustable in an adjustment direction axially parallel to the printing machine cylinder for adjusting the two clamping bars in a respective tautening direction thereof, the second clamping bar being supported on the printing machine cylinder via an adjustable stop.
In accordance with another feature of the invention, the adjustable stop is rotatable out of a blocking rotary position wherein the adjustable stop blocks an adjustment of the second clamping bar, into a released rotary position wherein the adjustable stop enables the adjustment of the second clamping bar.
In accordance with a further feature of the invention, the adjustable stop is a two-position eccentric.
In accordance with an added feature of the invention, the first clamping bar is supported on the printing machine cylinder via a spring.
In accordance with a third aspect of the invention, there is provided a device for locking a cylinder dressing on a printing machine cylinder, with a first clamping bar and a second clamping bar, comprising at least one adjusting member adjustable in an adjusting direction axially parallel to the printing machine cylinder for adjusting the two clamping bars in a respective tautening direction thereof, and together therewith forming a floating system supported on the printing machine cylinder via a spring.
In accordance with another feature of the invention, a trailing edge of the cylinder dressing is fastenable to the first clamping bar, and the spring is interposed between the first clamping bar and the printing machine cylinder, so that the spring force of the spring acts upon the first clamping bar in the tautening direction thereof.
In accordance with a further feature of the invention, a leading edge of the cylinder dressing is fastenable to the second clamping bar, and the spring is interposed between the second clamping bar and the printing machine cylinder, so that the spring force of the spring acts upon the second clamping bar counter to the tautening direction thereof.
In accordance with an added feature of the invention, the first clamping bar is supported on the second clamping bar via another spring.
In accordance with an additional feature of the invention, the other spring has a more rigid action than the first-mentioned spring.
In accordance with yet another feature of the invention, the device includes at least one thrust wedge formed on each of the two clamping bars, the adjusting member being pressable during the adjustment thereof on the at least one thrust wedge for thereby adjusting the clamping bars in the tautening direction thereof.
In accordance with yet a further feature of the invention, the adjusting member is an adjusting crossmember displaceable in the axially parallel direction.
In accordance with a third aspect of the invention, there is provided a printing machine having at least one device for locking a cylinder dressing on a cylinder thereof, the device having a first clamping bar and a second clamping bar, and comprising at least one adjusting member adjustable in an adjustment direction axially parallel to the printing machine cylinder for adjusting the two clamping bars in a respective tautening direction thereof, the second clamping bar being supported on the printing machine cylinder via an adjustable stop.
In accordance with a concomitant feature of the invention, the one adjusting member is capable of adjusting both of the clamping bars.
In accordance with an alternative feature of the invention, the at least one adjusting member constitutes an individual adjusting member for each of the first and the second clamping bars.
The pressman, when performing the method according to the invention, is no longer required to tighten a large number of screws or to adjust any adjusting bolts, but instead, effects a quick-action tautening of the cylinder dressing essentially by a single actuation of the adjusting member. The adjustment of the adjusting member and, if appropriate, an additional adjustment of an adjustable stop can be effected without difficulty by an electromotive or pressure fluid-loadable remotely controllable adjusting or setting drive, so that the method can be performed not only manually, but also in a completely or partially automated manner.
Despite the pulling or drawing of the two dressing edges, the positional accuracy of the cylinder dressing is always assured when it is subjected to tension at both ends and is therefore uniformly taut in the circumferential direction. For this purpose, in the second method step, the clamping bars can be adjusted towards one another in the respective tensioning or tautening direction and relative to the printing machine cylinder over adjustment paths which differ in length from one another.
The two devices according to the invention are based upon the same principle, as explained hereinbelow.
The first device according to the invention for clamping or locking a cylinder dressing on a printing machine cylinder, with a first clamping bar and a second clamping bar, is distinguished in that the two clamping bars are adjustable in the respective tautening or tensioning direction thereof by the same or a respective adjusting member adjustable in an adjusting direction axially parallel to the printing machine cylinder, and the second clamping bar is supported on or braced against the printing machine cylinder via an adjustable stop.
This device has only a few operating locations in the form of a single adjusting member or of two adjusting members, plus the adjustable stop, and is very suitable for effectively performing the method according to the invention. In this regard, the device functions in a manner that, in the first method step, only the first clamping bar is adjusted in the tautening or tensioning direction thereof relative to the printing machine cylinder and, in the second method step, both clamping bars are adjusted in the tensioning direction thereof relative to the printing machine cylinder, in the second method step the second clamping bar being adjusted over a longer adjustment path than the first clamping bar.
Successive adjustment of the clamping bars is achieved by the adjustment of the adjustable stop taking place between the method steps. After the adjustable stop has been released, the two clamping bars are adjustable as a unit in the form of a so-called floating lock-up system.
A second device according to the invention for the clamping or locking up a cylinder dressing on a printing machine cylinder, with a first clamping bar and a second clamping bar, is distinguished in that the two clamping bars are adjustable in the respective tensioning or tautening direction thereof by the same or a respective adjusting member adjustable in an adjusting direction axially parallel to the printing machine cylinder and together form a floating system supported on or braced against the printing machine cylinder via a first spring.
This device, too, has only a few operating locations in the form of the common adjusting member or the respective adjusting members, as the case may be, and is likewise very suitable for effectively performing the method according to the invention.
In this regard, the device functions so that, in the first method step, the first clamping bar is adjusted in the tensioning or tautening direction thereof relative to the printing machine cylinder and the second clamping bar is not adjusted, and so that, in the second method step, the second clamping bar is adjusted over a greater adjustment travel distance than the first clamping bar.
In this context, the staggered adjustment of the clamping bars is effected by the first spring which, during the first method step, temporarily fixes the second clamping bar in the position thereof, until the force acting on the first spring exceeds a specific amount, with the result that the first spring is tensioned or tautened, and the second clamping bar is therefore also adjusted in the tensioning or tautening direction thereof.
Both in the first and the second device according to the invention, provision may be made for the two clamping bars to have a common adjusting member assigned thereto that is adjustable in the axially parallel adjusting direction. Provision may also be made, in both devices, for the first clamping bar to have a first adjusting member assigned thereto that is adjustable in an adjusting direction axially parallel to the printing machine cylinder and for the second clamping bar to have assigned thereto just such an adjusting member for adjusting the respective clamping bar in a tensioning or tautening direction. The method and the devices are particularly suitable for the in-register clamping or locking-up of a varnishing or printing plate on a form cylinder of a rotary printing machine.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method and device for locking or clamping a cylinder dressing on a printing machine cylinder, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: